1. Field of the Invention
This invention provides methods of treating subterranean zones wherein particulate solids are placed in the zones to prevent the transport of formation fines therefrom.
2. Description of the Prior Art
The transport of formation fines, e.g., sand and the like, from subterranean zones or formations with produced fluids is very detrimental in that the formation fines erode metal goods, plug piping and vessels and cause damage to valves, instruments and other production equipment. Such formation fines are generally available for transport from unconsolidated subterranean zones or formations.
In order to prevent the transport of formation fines from subterranean producing zones, particulate solids have been placed in the well bores or formations penetrated thereby such as by gravel packing or propped fracturing. In gravel packing treatments, particulate solids such as graded sand (referred to in the art as gravel) is suspended in a treating fluid and carried to a subterranean zone in which a gravel pack is to be placed. Once the gravel is placed in the zone, the treating fluid is recovered or allowed to dissipate into subterranean formations penetrated by the well bore. The gravel pack functions as a filter to separate formation fines from produced formation fluids while permitting the produced fluids to flow into and through the well bore. In fracturing treatments, a treating fluid is pumped through a well bore into a subterranean zone to be stimulated at a rate and pressure such that fractures are formed and extended in the subterranean zone. Particulate solids (referred to in the art as proppant particles) such as graded sand are carried into the fractures by the treating fluid. The proppant particles are deposited in the fractures and the treating fluid is recovered. The proppant particles function to prevent the formed fractures from closing whereby conductive channels are formed through which produced fluids can flow to the well bore.
While gravel packs and propped fractures have been used successfully to reduce or prevent the transport of formation fines, a problem very often encountered is the flow-back of gravel or proppant particles which leads to the transport of formation fines with hydrocarbon and other fluids produced from the subterranean zone. Like formation fines, the flow-back of gravel or proppant particles from gravel packs or propped fractures with or without formation fines erodes metal goods, plugs, piping and vessels and causes damage to valves, instruments and other production equipment.
A number of techniques have heretofore been developed to prevent gravel and proppant particle flow-back which include coating the gravel or proppant particles with a hardenable resin or a tackifying agent that consolidates the gravel or proppant particles into hard permeable masses. In addition, fibers, thermoplastic particulate, ribbons, flakes and other similar materials have been mixed with the gravel or proppant particles to prevent gravel or proppant flow-back. While the techniques utilized heretofore have been successful in limiting gravel or proppant particle flow-back, gravel or proppant particle flow-back still occurs. Thus, there is a continuing need for improved methods of treating subterranean zones penetrated by well bores whereby gravel or proppant particle flow-back and/or the transport of formation fines from the subterranean zones are prevented.
The present invention provides improved methods of treating subterranean zones whereby particulate solid flow-back and the transport of formation fines from subterranean zones is reduced or prevented. The methods of the present invention are basically comprised of the following steps. A treating fluid having a mixture of reticulated foam fragments and particulate solids suspended therein is provided. The reticulated foam fragments are present in the treating fluid in an amount in the range of from about 0.1% to about 5% by weight of the particulate solids therein. The treating fluid is introduced into the subterranean zone and the mixture of the reticulated foam fragments and the particulate solids are deposited in the subterranean zone. The presence of the reticulated foam fragments in the mixture of the fragments with particulate solids reduce or prevent the flow-back of the particulate solids and the transport of formation fines from the subterranean zone upon producing fluids from the zone.
A method of fracturing a subterranean zone is also provided by the present invention comprised of the following steps. A fracturing fluid having proppant particles suspended therein is provided. Reticulated foam fragments are combined with the fracturing fluid to thereby form a mixture of the reticulated foam fragments with the proppant particles suspended in the fracturing fluid. The reticulated foam fragments are present in the fracturing fluid in an amount in the range of from about 0.1% to about 5% by weight of the proppant particles therein. The fracturing fluid is introduced into the subterranean zone at a rate and pressure sufficient to extend fractures in the subterranean zone. Thereafter, the mixture of the reticulated foam fragments and proppant particles is deposited in the subterranean zone whereby the reticulated foam fragments reduce or prevent the flow-back of the proppant particles and the transport of formation fines from the subterranean zone upon producing fluids from the zone.
The objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows when taken in view of the accompanying drawings.